Fine processing by lithography using a photoresist has been conventionally carried out in production of a semiconductor device. The fine processing is a processing method in which a thin film of the photoresist is formed on a semiconductor substrate such as a silicon wafer, irradiated with an active light such as ultraviolet light through a mask pattern that has a pattern of the semiconductor device, and developed, and the substrate is etched using the obtained photoresist pattern as a protective film to form fine concaves and convexes corresponding to the pattern on a surface of the substrate. In recent years, an increase in degree of integration of the semiconductor device has advanced, and shorter wavelength active light tends to be used from a KrF excimer laser (248 nm) to an ArF excimer laser (193 nm) or EUV light (13.5 nm). For this reason, influence of reflection of active light from the semiconductor substrate is a sever problem.
As an underlayer film between a semiconductor substrate and a photoresist, a film that contains silicon or the like and is conventionally known as a hard mask has been used (for example, see Patent Document 1). In this case, constituent components of the resist and the hard mask (underlayer film) are largely different. Therefore, rates of removing the constituent components by dry etching largely depend on the type of gas used in the dry etching. When the type of gas is appropriately selected, only the hard mask can be selectively removed by dry etching without a large decrease in the film thickness of the photoresist.
In the recent production of a semiconductor device, a resist underlayer film is disposed between the semiconductor substrate and the photoresist in order to achieve various effects including an effect of preventing the reflection. Although a composition for the resist underlayer film has been investigated, development of a novel material for the resist underlayer film is desired to meet diverse properties that the resist underlayer film is required to have.
In such a circumstance, a resist underlayer film formed from a resist underlayer film-forming composition containing a polyorganosiloxane obtained using a constant amount of silane compound having a sulfonyl bond improves the dry etching rate relative to a resist as an upper layer and has resistance to dry etching during processing a substrate, and the shape of a resist pattern after exposure and development is a rectangular. It has recently been found that the composition allows substrate processing using a fine pattern (see Patent Document 2).